Method of drawing glass cylinders.



A. E. SPINASSB. METHOD OF DRAWING GLASS CYLINDERS.

APPLICATION FILED MAY 14, 1913.

1,085,066, Patented Jan. 20 1914.

ARTHUR E. SPINASSE, OF MOUNT VERNON, OHIO.

marnon on naawme cus vtm aas- Specification of Letters Patent.

Patented Jan. 20, 1914.

Application men ma 14,1913. Serial No. 767,823.

To all whom it may concern:

Be it known that I, ARTHUR E. SrmAssn, a citizen of the United States of America, residing at Mount Vernon, in the county of Knox and State of Ohio, have invented certain new and useful Improvements in Methods of Drawing Glass Cylinders, of whichthe following is *a specification.

My invention relates to the art of drawing glass cylinders or rollers, as they are known in the art, and may be aptly characterized a method of drawing glass cylinders. While it is a method of drawing glass cylinders, it is more exactly'a. method of using a particular form of bait, which may be called a pocket-bait. The meaning of this term will be more clear by reference to my patent numbered 921,747 which shows and contains claims upona pocket bait. My present invention is a method of use of a bait of this type, wherein there is provided a pocket adapted to receive and retain the initial portion of a cylinder to be drawn.

The primary purpose of this method is the production of an initial portion of the cylinder to be drawn which initial portion will well support the cylinder from the bait throughout the drawing act-ion and in a manner such that breakage of the initial portion of the cylinder will be precluded.

Because the result to be attained may not be readily reached and because the attainment is fraught with many difliculties which have, I believe, never been plainly apparent to the many prior intelligent inventors, I deem it necessary to here state the basic causes of these difficulties, since in no other way can the importance of my invention be realized. I, therefore, here state the broad principles which have hitherto been ignored, with failure as a result, and upon which my invention is founded, with success as. a result. The bait, usually of metal,

is dipped in a molten glass bath to gather I i the initial portion of the cylinder and is then withdrawn and slowly elevated, the elevation being accompanied by the introduction of air to the center of the gather to expand it to cylindrical form. This is apparently a simple operation. The difficulty primarily arises from the fact that there: necessarily results either a band of metal surrounding a body of glass or vice versa,

these two materials of course having different coefficients of expansion. Of almost equal importance 'is the fact that'one mapansion the same as that of glass.

terial is giving up while, the other is ,ab-

sorbing heat and, furthermore, the giving a up and the absorption cannot be the same or uniform in different parts of the materials. To illustrate, if the material of the bait and the glass had the same coeflicients of expansion and were uniformly heated at all points, they would expand and contractequally and in harmony at all points. But we at once face the fact that there is no material known which has a coefiicient of ex- Another fact of equal importance is also apparent, that is, that it is practically impossible to attain and maintain a uniform heating throughout the drawing operation. At this point it may be well that we remember the extreme importance of even minute variations of form, in the handling of this brittle glass before it is annealed. Ample reason .for the lack of uniformity in heating appears from the fact that the surface of the lass at a drawing temperature is in the neig borhood of 1500 degrees, while the substrata increase in temperature with their depth until a certain depth is reached. With any-ordinary metal, the bait must initially be at a lower temperature than the glass. It follows that there will result an interchange of heat between the glass and the bait during the draw, the glass yielding up its heat and contracting, while the bait absorbs heat and expands, up to a certain point. At some time, probably during the expansion of the bait, the gather sets to permanent form and continues to cool and probably to slightly shrink. The bait may continue to expand and probably will, but

it will ultimately contract and return to normal position. These expansions and contractions of the glass and the bait relatively are not only irregular in relation to each other, but the glass may contract more at one point than at another during a, certain period and the bait may expand or contractmore at one point than at another during a certain period. The variant expansion of the bait at different points is es ecially pronounced in certain types of baits, although it is apparently inevitable to some extent in all types.

My invention consists in a a method. of avoiding conflicts which would ordinarily arise from the above conditions in the drawing of glass cylinders. It aims to produce a cylinder whose initial portion is supported in easy relation by the bait. Specifically stated, my method produces an inltial portion of the cylinder which is supported by relation to the bait, or direct rupturing pressures will arise.

My invention relates, as stated, to a pocketbait and has for its object the production of a nowel supported in the bait pocket without fusion and properly shaped to avoid rupturing pressures of a direct nature. My method of use of this pocket-bait comprises two steps. The first step is the use of the bait comparatively cold to produce a plastic nowel which is well supported in the pocket of the bait but without fusion to the walls of such pocket. The second step consists in permitting the nowel to set naturally to ex ternal permanence of form and size before the cylinder-producing air is introduced through such nowel. Many equivalents are possible. For instance, instead of usingthe bait cold, it may be possible to use a graphite of some kind; or, instead of permitting the nowel to completely set before blowing, it may be possible and advisable to blow with very slight pressure before the nowel has fully set. In the first instance, it is the enda non-fused nowelthat is sought. In the second instance, it is the proper shape. I claim the right to equivalents.

In specifying that the bait should be used comparatively cold, I mean that the bait at the time of insertion should be at a temperature probably less than 200 degrees F. in

'contradistinction to the custom, hitherto so" prevalent, of using the bait at a temperature of approximately 800 degrees F. Of course circumstances may alter this temperature.

I have considered it advisable to utilize drawings in the explanation of my invention and, in these drawings, Figure 1 is a vertical section ofa bait and nowel with indications of the temperatures existing at the different points, it being understood that.

these temperature indications are not true but are merely illustrative of the different temperature conditions at different points on the bait and nowel and showing relative conditions. Fig. 2 is a vertical section of a bait and nowel wherein the bait is being held near the surface of the glass bath until its external contour becomes practically unalterable'. It will be understood that this may be accomplished in otherways, as by drawing slowly. Fig. 3 is a vertical section of a bait and the initial portion of the cylinder, showing the relation of this initial portion of the cylinder to the bait.

In the drawings, I have shown one form of pocket-bait, which may be utilized, as comprising a body carried by a pipe'2. The bait has been used comparatively cold, as stated above, and has been dipped in the bath to gather the glass, although the glass might be gathered by suction. From the moment the bait approaches the surface of the glass bath, it commences to absorb heat and the glass in immediate subjection there.- to commences to lose heat. This interchange of heat is necessarily more pronounced during and after dipping. As the nowel contracts with the cooling the upper end thereof settles back. In the use of the form of bait shown in Fig. 2, it is particularly necessary to limit the height of the nowel on its sup porting surfaces. By reference to Fig. 1 of the drawings, it will appear that this upper end of the bait will be the coolest point during the drawing operation, it being apparent independently of the drawings that such upper end of the bait is the least subject to heat influences. Therefore, this portion of the baitand nowel which may be designated A is the least subject to the dangers of confiicting contractions and expansions.

The real danger zone of the operation may be indicated approximately by vB and this will be understood by a comparison of the temperatures of the bait and the nowel at this point, or by contemplation of the fact that this part of the bait is the first part to enter and the last part to leave the hot lass bath. Not only does the bait expan more at this point but the nowel is, particularly in the initial stage of the drawing, variable as to form under the slightest influences. The expansion of the bait in the neighborhood of the zone B is represented by the dotted lines in Fig. 1. Now, though the bait expands to such an extent, it must not be forgotten that the contraction is substantially equal. To illustrate the danger, let it be supposed that the bait has started to expand and will have a total expansion of one-sixteenth of an inch. After one half of the expansion has taken place or, to put it another way, after the bait has expanded one-thirty-second of an inch, suppose the blowing of the cylinder is initiated in the normal way. The nowel, which is still very sensitive particularly at B, will be expanded so that this portion B will be blown into contact with the orificial wall of the bait. Then, suppose the nowel sets at this point. The bait will continue to expand for another thirty-second of an inch.

size than the set nowel.

Correction in Letters Patent No. 1,085,066.

Then, contraction of the bait will set in and the bait will ultimately contract to its normal size, or very nearly so. At any rate, the bait will ultimately contract to a smaller This must result in the crushing of the nowel. The second step of my invention eliminates this last-described danger by attaining such a shape of nowel that the variations of the bait and nowel do not conflict, at least to any material extent. By way of reiteration, this second step consists in permitting the nowel to naturally set to external permanence of form before blowing. My method, the-n, consists in using the bait cold or in such a state as to produce a non-fused nowel and permitting such nowel to naturally set to external permanence of form before blowing. It will be apparent that the nowel must be non-fused or the second step of the process will be useless. It will be equally apparent that the nowel must be permitted to set naturally before blowing or the process will be incomplete. The two steps are necessary and inseparable in the present process.

In this application,the word nowel has been used to denote both the portion which is in actual contact with the bait and the neck which connects this portion with the cylinder. The word naturally means [scan] that state wherein the neck of the nowel or any portion thereof will not be forced into dangerous proximity to any abrupt wall of the bait. This forcing might occur either because of the form of the bait or by its accessory elements or by the air. Figs. 2 and 3 are particularly presented to show the desirable clearance attained at B by my method. Permitting to set to an external permanence of contour embraces immaterial variations, it having been made clear that the object is to avoid dangerous proximity of abrupt walls of the bait and the nowel.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

The method of drawing glass with a'bait having a nowel supporting pocket which consists in using the said bait cold to procure It is hereby certified that in Letters Patent No. 1,085,066, granted January 20, 1914, upon the application of Arthur E. Spinasse, of Mount Vernon, Ohio, for an improvement in Methods of Drawing Glass Cylinders, an error appears in the printed specification requiring correction as follows: In the specification and claim, wherever occurring, for the word nowell read novel;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case inthe Patent Oflice.

Signed andsealed this 10th day of March, A. D., 1914..

R. T. FRAZIER,

Acting Commissioner of Patents. 

